Floodwall Embankment Project


The concrete embankment and floodwall on the eastern perimeter of the District’s wastewater treatment facility was damaged by the massive debris flow event in Carpinteria Creek on January 9, 2018, which followed the Thomas Fire.  The foundation supporting the structure was undermined and partially destroyed by what may have been the highest ever recorded flow in the creek.   Response to the damage included an interim effort to stabilize the embankment and a more significant construction project to replace the damaged infrastructure.


Due to the sensitive environmental habitat within the creek corridor, the District worked diligently to obtain the required permits for the interim work and the the permanent repair.  Approvals were granted by the California Coastal Commission, the US Army Corps of Engineers, the US Fish and Wildlife Service, the National Marine Fisheries Service, and the Central Coast Regional Water Quality Control Board.  Design and construction measures were implemented in order to minimize impacts to the creek environment, to protect sensitive species and to restore the habitat to pre-disaster conditions.  In fact, the finished product has elements that should markedly improve habitat for Southern Steelhead Trout and other sensitive species.


The project involved in-kind replacement of approximately 210 linear feet of foundation that was destroyed by the debris flow.  A steel sheet pile wall was installed using vibratory methods below the maximum anticipated scour depth.  A reinforced concrete block foundation was constructed between the new wall and the toe of the embankment and soil was placed over the new foundation to provide a substrate for arroyo willow plantings and other native plant species.  The repair work was funded, in large part, by disaster recovery grant from the Federal Emergency Management Agency (FEMA) and the California Office of Emergency Services (CalOES).  The total project cost was in excess of one million dollars.